showing picker inside a listview

Question

Hi all,
I am working with the ListView where my requirement is to show a picker inside it, but I am facing an error like this

System.ArgumentNullException: 'Value cannot be null. Parameter name: element'

for more information, I have shared a code in the below link
https://stackoverflow.com/questions/65194822/system-argumentnullexception-value-cannot-be-null-parameter-name-element-ge/65200853#65200853